A panel, it its simplest form, may comprise of a sheet of material. It can be single ply or multi-ply. The desirable attributes of the panel would depend on the situation it is required for. For instance, a panel used as a covering would be expected to be less rigid than a panel used for a roof and a panel used as a platform which people stood or walked upon would need to have resistance to lateral point stresses in addition to being rigid.
By increasing the thickness of the panel (or by adding more sheets and varying the gap between those sheets) the same material may be used for a panel in which the rigidity and strength can be varied. An increase in thickness of the material will increase the amount of material used and this in turn this would increase the weight and costs of the material. Instead just varying the space between the sheets or plies can achieve similar strength or rigidity changes, but without the considerable increase in material costs—only the material cost of any additional spacing materials would be incurred.
It is known to use these techniques to increase the strength of a panel whilst minimising the increase in material used. Other techniques are also known. These include varying of the shape of the panel, such as using corrugations, or by using composites where different materials are combined, such as foam filled fibreboard. Another method is to combine these techniques, for example where a shaped material forms the internal structure of a panel. These methods are not without their own issues: such structures may result in unidirectional strength, or additional costs in the manufacture of the complex structures, and more costly recycling in the case of composites, and this can outstrip the benefit of the material saving.
It would therefore be desirable to create a structural element where, compared to a sheet of material, the strength can be increased without the addition of further material, and thus weight. It would also be desirable for the structural element to be versatile, for example not having a preferred orientation for its use. It would also be desirable for the structural element to be easy to manufacture.